Contacting terminal structure for electrical devices



Sept. 13, 1938. M. LAZARUS 2,129,947

CONTACTING TERMINAL STRUCTURE POP. ELECTRICAL DEVICES Filed Aug. 6, 1936lNVENTOR MEYER A AZ/l/PMS ATTORNEY Patented Sept. 13, 1938 UNITED STATESPATENT OFFICE CONTACTING TERMINAL STRUCTURE FOR ELECTRICAL DEVICESApplication August 6, 1936, Serial No. 94,525

2 Claims.

My invention relates to improvements in contacting terminal structuresfor electrical devices, such as copper oxide rectifying elements,resistance elements and the like; and it consists in 6 the novelfeatures which are hereinafter described.

One of the objects of my invention is to provide perfected inexpensivecontacting terminal structures for electric rectifiers, resistance ele-10 ments and the like, whereby high pressure may be avoided inassembling the discs of said rectifiers and resistance elements into astack.

Another object is to reduce the aging of the terminals to wit: toprevent an increase of re- 18 sistance at the junction of the terminalsand the .said discs due to oxidation.

A further object is to enable the said terminal structures to withstandrelatively high temperatures.

adapted for mass production.

Another object of my invention is to reduce the electrical resistance atthe junction of the terminals of the said devices and thereby reduce thecontact drop.

Other objects and advantages will hereinafter appear.

I attain these objects by the electrical devices and the contactingterminal structures thereof which are illustrated in the accompanyingdrawing or by any mechanical equivalents or obvious modifications of thesame.

In the drawing, Fig. l is a vertical section of an electrical devicecontaining a single element and embodying one form of my contactingterminal structure which is shown as connected thereto.

Fig. 2 shows a stack of elements of the electrical device which is shownin Fig. 1. Each of these elements includes a contacting terminalstructure.

Fig. 3 is a view partly in section and partly in elevation of anotherelectrical device embodying my contacting terminal structure which isshown as connected to each of the opposite sides of the said device.

The thickness of the sundry plates and layers is exaggerated in all thefigures of the drawing.

Similar numerals refer to similar parts throughout the several views:

In the modification of my improved electrical device, which is shown inFig. 1, ll designates a metal carrier of an electrical element, whichmay 1 5 be either a resistance element or a rectifying ele- Stillanother object is to have said devices ment, and i2 a layer of oxide ofthe metal of the carrier H, which is integral therewith.

The carrier ll may be made of copper and the layer l2 of cuprous oxide.

Instead of an oxide any other poor conductor, such as an iodide, atelluride, a sulphide or a selenide, may be employed in some cases, ifdesired.

A contacting plate l3 which may be a metal plate is shown as connectedto the layer ii on the side of the latter which is remote from saidcarrier ii and a coating ll of a substance known in the arts asgraphalloy, preferably babbitt graphalloy, is shown as placed betweenthe layer l2 and the terminal plate l3 and in contact with said platei3. Lead graphalloyf, tin gradphalloy or lead and tin graphalloy may beuse Graphalloy is an imperfect alloy or conjunction of graphite and asoft metal produced by filling the interstices of porous graphite withthe metal in a state of fusion.

The coating It may first be formed on said layer I! by rubbing the layerI! or a part thereof with a piece of the graphalloy, which may have asuitable shape.

I prefer to cover with the coating ll only a portion of the surface ofthe layer l2 opposite the plate, l3, to prevent any portion of the layerll from being brought into contact with the carrier ll through cracks atthe inner and outer peripheries of said layer i2, to avoid shortcircuiting the element |I-i4.

The operation of coating the layer I! with the said graphalloy may bedone either manually or by any suitable machine or contrivance.

Both the layerii and the plate l3 may be coated with said graphalloy, ifdesired, but I prefer to form the coating on the layer II.

The said disc at the surface of contact thereof with the coating M willmaintain a substantially constant and low contact resistance with thecoating it without an increase of resistance at the junction or contactsurface thereof.

The said disc is also adapted to withstand very high temperatures.

Instead of graphalloy any other imperfect alloy or conjunction of carbonwith a soft metal may be used, but I prefer an imperfect alloy orconjunction of graphite and Babbit metal.

The coating l4 serves to. fill the inequalities and interstices on thelayer l2 and forms thereon a thin, firmly adhering, nonoxidizable film,which I found to produce a low contact drop between said layer l2 andsaid plate I3.

The metal "graphalloy" has a higher electrical conductivity thangraphite.

Wires i1 and II are connected to the plate I! and the carrier ll.

Fig. 2 shows a stack oi multiple discs ii of the same type as shown inFig. 1. Only one plate II is shown as employed at one end of the stack,and a terminal plate lie is shown as connected to the other end 01' the-stack. The adjacent discs ll of the stack serve as contacting plates ofthe device.

Wires l1 and II are connected to the plates l0 and lid.

In the modification of my electrical device, which is shown in Fig. 3and is a resistance unit, a disc 22 of oxide. preferably cuprous oxide,is shown as having on the opposite sides thereof coatings 24 01'graphalloy"; a sheet 25 of metal toll is shown as in contact with eachof the said coatings 24. A terminal plate 26 is shown as in contact witheach of said sheets 25. Wires i1 and II are shown as connected to saidterminals 28. Discs of insulation 21 are shown as in contact with saidterminals 28.

Pressure plates 2' are shown as applied to the discs 11 at the ends oi.the unit. The discs 21 serve to insulate the terminals 26 from saidplates 2|.

A bolt 2. having thereon a head 29a and a nut 30 in engagement with saidbolt 29 are shown as holding and pressing together all the abovedescribed parts of the complete unit. The bolt It is encompassed by asleeve 23 of insulating material.

Variations are possible and parts of my invention' may be used withoutother parts.

Theterm an oxide and the like," as used in the claims hereinafter, ismeant to include also a selenide and a sulphide.

I claim as my invention, and desire to secure by Letters Patent:

1. A terminal structure for an electrical device including a contactingplate, a metal plate carrier and a layer of an oxide of said carrier onsaid carrier, a fllm 0! an alloy of graphite and a soft metal on saidlayer, firmly adhering thereto, interposed between said layer and saidcontacting plate, the metal of the alloy of said mm extending intocontact with both said layer and said contacting plate and filling theinequalities and interstices in the bodies of both said layer and saidcontacting plate on the adjacent sides of the same, thereby enhancingthe conductivity through the body of said terminal structure.

2. The method of making a terminal structure for an electrical devicecomprising a contacting plate, a metal carrier and a layer 01' an oxideof the carrier on said carrier integral with the latter, consisting inrubbing an alloy of graphite and a soft metal on said layer, said alloythereby being made firmly to adhere to the said layer and to extend intoand fill the inequalities and interstices in the body of said layer onthe side thereoi which is adjacent to the contacting plate.

MEYER LAZARUS.

